mirror of http://galexander.org/git/simplesshd.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
269 lines
6.7 KiB
269 lines
6.7 KiB
.ds d \-\^\-
|
|
.ds o \fR[\fP
|
|
.ds c \fR]\fP
|
|
.ds | \fR|\fP
|
|
.de D
|
|
\\.B \*d\\$1
|
|
..
|
|
.de DI
|
|
\\.BI \*d\\$1 \\$2
|
|
..
|
|
.de DR
|
|
\\.BR \*d\\$1 \\$2
|
|
..
|
|
.de Di
|
|
\\.BI \*d\\$1 " \\$2"
|
|
..
|
|
.de Db
|
|
\\.B \*d\\$1 " \\$2"
|
|
..
|
|
.de Df
|
|
\\.B \*d\*ono\*c\\$1
|
|
..
|
|
.de See
|
|
See \fB\\$1\fP for details.
|
|
..
|
|
.de SeeIn
|
|
See \fB\\$1\fP in \fB\\$2\fP for details.
|
|
..
|
|
.TH POOL_ALLOC 3
|
|
.SH NAME
|
|
pool_alloc, pool_free, pool_free_old, pool_talloc, pool_tfree, pool_create, pool_destroy, pool_boundary
|
|
\- Allocate and free memory in managed allocation pools.
|
|
.SH SYNOPSIS
|
|
.B #include "pool_alloc.h"
|
|
|
|
\fBstruct alloc_pool *pool_create(size_t \fIsize\fB, size_t \fIquantum\fB, void (*\fIbomb\fB)(char *), int \fIflags\fB);
|
|
|
|
\fBvoid pool_destroy(struct alloc_pool *\fIpool\fB);
|
|
|
|
\fBvoid *pool_alloc(struct alloc_pool *\fIpool\fB, size_t \fIsize\fB, char *\fImsg\fB);
|
|
|
|
\fBvoid pool_free(struct alloc_pool *\fIpool\fB, size_t \fIsize\fB, void *\fIaddr\fB);
|
|
|
|
\fBvoid pool_free_old(struct alloc_pool *\fIpool\fB, void *\fIaddr\fB);
|
|
|
|
\fBvoid *pool_talloc(struct alloc_pool *\fIpool\fB, \fItype\fB), int \fIcount\fB, char *\fImsg\fB);
|
|
|
|
\fBvoid pool_tfree(struct alloc_pool *\fIpool\fB, \fItype\fB, int \fIcount\fB, void *\fIaddr\fB);
|
|
|
|
\fBvoid pool_boundary(struct alloc_pool *\fIpool\fB, sise_t \fIsize\fB);
|
|
.SH DESCRIPTION
|
|
.P
|
|
The pool allocation routines use
|
|
.B malloc()
|
|
for underlying memory management.
|
|
What allocation pools do is cause memory within a given pool
|
|
to be allocated in large contiguous blocks
|
|
(called extents) that will be reusable when freed. Unlike
|
|
.BR malloc() ,
|
|
the allocations are not managed individually.
|
|
Instead, each extent tracks the total free memory within the
|
|
extent. Each extent can either be used to allocate memory
|
|
or to manage the freeing of memory within that extent.
|
|
When an extent has less free memory than a given
|
|
allocation request, the current extent ceases to be used
|
|
for allocation. See also the
|
|
.B pool_boundary()
|
|
function.
|
|
.P
|
|
This form of memory management is suited to large numbers of small
|
|
related allocations that are held for a while
|
|
and then freed as a group.
|
|
Because the
|
|
underlying allocations are done in large contiguous extents,
|
|
when an extent is freed, it can release a large enough
|
|
contiguous block of memory to allow the memory to be returned
|
|
to the OS for use by whatever program needs it.
|
|
You can allocate from one or more memory pools and/or
|
|
.B malloc()
|
|
all at the same time without interfering with how pools work.
|
|
.P
|
|
.B pool_create()
|
|
Creates an allocation pool for subsequent calls to the pool
|
|
allocation functions.
|
|
When an extent is created for allocations it will be
|
|
.I size
|
|
bytes.
|
|
Allocations from the pool have their sizes rounded up to a
|
|
multiple of
|
|
.I quantum
|
|
bytes in length.
|
|
Specifying
|
|
.B 0
|
|
for
|
|
.I quantum
|
|
will produce a quantum that should meet maximal alignment
|
|
on most platforms.
|
|
Unless
|
|
.B POOL_NO_QALIGN
|
|
is set in the
|
|
.IR flags ,
|
|
allocations will be aligned to addresses that are a
|
|
multiple of
|
|
.IR quantum .
|
|
A
|
|
.B NULL
|
|
may be specified for the
|
|
.I bomb
|
|
function pointer if it is not needed. (See the
|
|
.B pool_alloc()
|
|
function for how it is used.)
|
|
If
|
|
.B POOL_CLEAR
|
|
is set in the
|
|
.IR flags ,
|
|
all allocations from the pool will be initialized to zeros.
|
|
If either
|
|
.B POOL_PREPEND
|
|
or
|
|
.B POOL_INTERN
|
|
is specified in the
|
|
.IR flags ,
|
|
each extent's data structure will be allocated at the start of the
|
|
.IR size -length
|
|
buffer (rather than as a separate, non-pool allocation), with the
|
|
former extending the
|
|
.I size
|
|
to hold the structure, and the latter subtracting the structure's
|
|
length from the indicated
|
|
.IR size .
|
|
.P
|
|
.B pool_destroy()
|
|
destroys an allocation
|
|
.I pool
|
|
and frees all its associated memory.
|
|
.P
|
|
.B pool_alloc()
|
|
allocates
|
|
.I size
|
|
bytes from the specified
|
|
.IR pool .
|
|
If
|
|
.I size
|
|
is
|
|
.BR 0 ,
|
|
.I quantum
|
|
bytes will be allocated.
|
|
If the pool has been created without
|
|
.BR POOL_NO_QALIGN ,
|
|
every chunk of memory that is returned will be suitably aligned.
|
|
You can use this with the default
|
|
.I quantum
|
|
size to ensure that all memory can store a variable of any type.
|
|
If the requested memory cannot be allocated, the
|
|
.I bomb()
|
|
function will be called with
|
|
.I msg
|
|
as its sole argument (if the function was defined at the time
|
|
the pool was created), and then a
|
|
.B NULL
|
|
address is returned (assuming that the bomb function didn't exit).
|
|
.P
|
|
.B pool_free()
|
|
frees
|
|
.I size
|
|
bytes pointed to by an
|
|
.I addr
|
|
that was previously allocated in the specified
|
|
.IR pool .
|
|
If
|
|
.I size
|
|
is
|
|
.BR 0 ,
|
|
.I quantum
|
|
bytes will be freed.
|
|
The memory freed within an extent will not be reusable until
|
|
all of the memory in that extent has been freed with one
|
|
exception: the most recent pool allocation may be freed back
|
|
into the pool prior to making any further allocations.
|
|
If enough free calls are made to indicate that an extent has no
|
|
remaining allocated objects (as computed by the total freed size for
|
|
an extent), its memory will be completely freed back to the system.
|
|
If
|
|
.I addr
|
|
is
|
|
.BR NULL ,
|
|
no memory will be freed, but subsequent allocations will come
|
|
from a new extent.
|
|
.P
|
|
.B pool_free_old()
|
|
takes a boundary
|
|
.I addr
|
|
value that was returned by
|
|
.B pool_boundary()
|
|
and frees up any extents in the
|
|
.I pool
|
|
that have data allocated from that point backward in time.
|
|
NOTE: you must NOT mix calls to both
|
|
.B pool_free
|
|
and
|
|
.B pool_free_old
|
|
on the same pool!
|
|
.P
|
|
.B pool_boundary()
|
|
asks for a boundary value that can be sent to
|
|
.B pool_free_old()
|
|
at a later time to free up all memory allocated prior to a particular
|
|
moment in time.
|
|
If the extent that holds the boundary point has allocations from after the
|
|
boundary point, it will not be freed until a future
|
|
.B pool_free_old()
|
|
call encompasses the entirety of the extent's data.
|
|
If
|
|
.I len
|
|
is non-zero, the call will also check if the active extent has at least
|
|
that much free memory available in it, and if not, it will mark the
|
|
extent as inactive, forcing a new extent to be used for future allocations.
|
|
(You can specify -1 for
|
|
.I len
|
|
if you want to force a new extent to start.)
|
|
.P
|
|
.B pool_talloc()
|
|
is a macro that takes a
|
|
.I type
|
|
and a
|
|
.I count
|
|
instead of a
|
|
.IR size .
|
|
It casts the return value to the correct pointer type.
|
|
.P
|
|
.B pool_tfree
|
|
is a macro that calls
|
|
.B pool_free
|
|
on memory that was allocated by
|
|
.BR pool_talloc() .
|
|
.SH RETURN VALUE
|
|
.B pool_create()
|
|
returns a pointer to
|
|
.BR "struct alloc_pool" .
|
|
.P
|
|
.B pool_alloc()
|
|
and
|
|
.B pool_talloc()
|
|
return pointers to the allocated memory,
|
|
or NULL if the request fails.
|
|
The return type of
|
|
.B pool_alloc()
|
|
will normally require casting to the desired type but
|
|
.B pool_talloc()
|
|
will returns a pointer of the requested
|
|
.IR type .
|
|
.P
|
|
.B pool_boundary()
|
|
returns a pointer that should only be used in a call to
|
|
.BR pool_free_old() .
|
|
.P
|
|
.BR pool_free() ,
|
|
.BR pool_free_old() ,
|
|
.B pool_tfree()
|
|
and
|
|
.B pool_destroy()
|
|
return no value.
|
|
.SH SEE ALSO
|
|
.nf
|
|
malloc(3)
|
|
.SH AUTHOR
|
|
pool_alloc was created by J.W. Schultz of Pegasystems Technologies.
|
|
.SH BUGS AND ISSUES
|